1. Field of the Invention
This invention relates to novel phenanthridines and phenanthridinones, to methods for their production, and to their use as intermediates and/or antiviral agents and as agents for stimulating interferon production of animals. More particularly, it relates to the control of virus infections in animals and to the induction of interferon in animals by oral parenteral, intranasal or topical adminstration of a mono- or bis-substituted[ .omega.-(di-lower alkyl)aminoalkoxy]phenanthridine or phenanthridinone.
2. Description of the Prior Art
The cells of vertebrates produce, in response to virus infection, a substance which enables cells to resist the multiplication of a variety of viruses. The viral-resisting or viral-interfering substances are referred to as "interferons." They are a heterogeneous group of antiviral proteins which vary quite widely in their molecular weights. Although such proteins may differ in their physico-chemical properties, they all exhibit the same biological properties; namely, they inhibit a wide range of unrelated viruses, have no toxic or other deleterious effects on the cells and are species-specific (Lockart, Frontiers of Biology, Vol.2, "Interferons," edited by Fintner, W. B. Saunder Company, Philadelphia, 1966, pp. 19-20).
The discovery of interferon by Isaacs and Lindenmann in 1957 (Proc. Roy. Soc. B., 147, 258-267) gave rise to great optimism that an economic preparation of exogeneous interferon might be developed for routine clinical use against viral infections. However, despite great expenditures of effort and money, no safe, effective economical source has yet been developed. An alternate approach to producing interferon has, therefore, been pursued. This approach comprises admistering to the animal to be protected, or treated, a non-viral substance which stimulates--or induces--production of interferon in the cells. The interferon produced in this fashion is referred to as "endogenous" interferon.
The discovery of antiviral compounds is far more complicated and difficult than is the discovery of antibacterial and antifungal agents. This is due, in part, to the close structural similarity of viruses and the structures of certain essential cellular components, such as ribonucleic and deoxyribonucelic acids, and to the difficulty of establishing suitable tests for evaluating antiviral agents. However, despite these difficulties, numerous non-viral substances have been found capable of stimulating or inducing interferon formation in animals. Included among such substances are bacteria, parasites, bacterial endotoxins, pyran copolymers, helenine, phytohemagglutinin, polyacrylic compounds, nucleic acids and polynucleotides. Use of these inducers is, however, objected to for one or more reasons, e.g., toxicity, antigenicity, infectiousness, and their routine clinical use appears remote (Zhdanov et al., Internat'l. Virol. I. 1st Int. Congr. Virol. Helsinki 1968, S. Karger, New York, pp. 100-1, 1969).
More recently 2,7-bis[2-(diethylamino)ethoxy]fluoren-9-one dyhydrochloride, a purely synthetic material of relatively low molecular weight, has been reported to be an oral inducer of interferon in mice (Abstracts Federation Proceedings, Vol. 29, No. 2, page 635, 1970; Abstracts 2189 and 2190).
A variety of "antiviral agents" are described in the literature. These have been summarized by Osdene in "Topics in Medicinal Chemistry," edited by Rabinowitz and Meyerson, Interscience Publishers, New York, 1968, pages 141-176. For the purpose of his review, Osdene has made use of Herrmann's definition of "antiviral agent" (Herrmann et al., Proc. Soc. Exptl. Biol. Med. 103, 635, 1960); namely, an agent "which can produce either a protective or therapeutic effect to clear detectable advantage of the virus-infected host, or any material that can significantly enhance antibody formation, improve antibody activity, improve non-specific resitance, speed convalescence or depress symptoms." This definition is of such breadth as to cover both prophylactic and therapeutic agents. It includes substances such as interferon, and a host of synthetic materials, such as 1-adamantanamine, pyrimidines, biguanides, guanidine, pteridines, to mention a few. It is noted that such synthetic materials are antiviral agents. They are not interferon inducers but operate by a totally different mechanism. Interferon inducers may, of course, be referred to as antiviral agents. The converse, however, is not necessarily true.
Virus infections which attack animals, including man, are normally contagious afflictions which may spread so rapidly that they can reach explosive, epidemic proportions in relatively short periods of time. In the past, many of these epidemics have resulted in large numbers of deaths and have been responsible to huge economic losses. Obviously, a method of reducing the incidence of these viral infections, such as the method of this invention, would be a valuable addition to the armamentarium of medical technology.